1. Technical Field
This invention relates generally to rechargeable batteries, and more particularly to rechargeable batteries having charging indicating means to be sensed by a sensing means of an electronic device or charger.
2. Background Art
Portable, battery-operated, electronic devices seem to be everywhere. From handheld games, to compact disc players, to radios, to personal data assistants, to phones, to pagers, it is becoming rare to encounter a person who does not carry at least one portable electronic device with them all the time. People carry the devices for entertainment, for organizational purposes, and for staying connected with others.
It is the battery of the device that provides portability. In the days before batteries, the user of an electronic device had to remain tethered to an electrical outlet by way of a wire and power supply. With the advent of batteries, however, portability was born. The most popular batteries in use to day are the so-called “primary”, or single-use, batteries made by companies including Eveready, Duracell and Energizer. These batteries, usually of alkaline chemistry, are readily available in stores, including grocery and drug stores. Common sizes of these batteries include AAA, AA, C, 9 Volt and D. They are often cylindrical in shape and are easily replaceable in electronic devices. They may be used until the stored energy is depleted, and they are then discarded.
While primary batteries are very convenient, they can become quite expensive for a user who constantly uses his electronic device. For example, a person who constantly listens to music on his portable stereo may have to replace as many as eight batteries on a weekly basis! This can become quite costly.
To alleviate this problem, rechargeable battery manufacturers now make rechargeable batteries in the same size and shape as the primary batteries. In other words, one is now able to purchase a rechargeable battery that looks and works just like an alkaline, primary battery. When the rechargeable battery dies, the user simply recharges it as opposed to buying a new one. The rechargeable nature of these batteries makes them quite economical.
The problem introduced by these rechargeable batteries is that they come in a variety of types and chemistries. Some may be nickel-based, while others are lithium-based. Additionally, within a particular chemistry family, some batteries may be designed to charge at high currents while others may only charge at lower currents. Improperly charging a battery may compromise its reliability. Thus, there is a need for a charger to be able to determine what type of battery is currently being used, and to adjust its charging voltage, current and procedure accordingly.
One prior art solution to this problem is to design different types of rechargeable batteries with different shapes, or “form factors”. For example, a 1 amp battery may have contacts that are ½” apart, while a 10 amp battery may have contacts that are ¾” apart. The problem with this solution is that it does not allow for interchangeability with primary use batteries. If a rechargeable battery is to be substituted for an AA alkaline battery, it must be of the same size and shape.
There is thus a need for a method and apparatus to determine the charging characteristics of a rechargeable battery.